1. Technical Field
The present disclosure relates to a mobile communication device with a voice call function and an echo cancellation method.
2. Description of the Related Art
In mobile communication devices such as a mobile phone and personal handyphone system (PHS), echo may occur when an incoming voice travels to be superimposed on an outgoing voice. As a technology for preventing such echo, Japanese Patent Application Laid-open No. 2008-182296 describes a mobile terminal device that includes a speaker and a microphone and also includes a sound insulator for insulating between the speaker and the microphone.
Some mobile communication devices are provided with a hands-free call function with which a user makes a phone call without holding the mobile communication device in hands. When the hands-free call function is used, by making louder a voice output from the speaker and increasing the sensitivity of the microphone, the mobile communication device enables the user to talk on it even being some distance therefrom. However, when the hands-free call function is used, echo easily occurs, and there is a case in which the echo cannot be prevented even if the sound insulator that insulates between the speaker and the microphone is provided as explained in the technology described in JP-A-2008-182296. In this case, by lowering the volume of the incoming voice or making mute the outgoing voice when the incoming voice is output like a transceiver, the echo can be reduced; however, the voice gets lower and it is thereby hard to follow conversations, which results in degradation of call voice quality.
For the foregoing reasons, there is a need for a mobile communication device and an echo cancellation method capable of reducing the echo and suppressing degradation of the call voice quality.